Various optical scanning devices have been employed to facilitate working with liquids, manufactured articles and detecting the presence of objects. For example, U.S. Pat. No. 4,538,072 discloses an optical wand that can be used for reading bar code marks that can be portable and usable in a plurality of applications. U.S. Pat. No. 4,525,071 reveals the use of bar code scanners in controlling and batching inventory delivery systems. U.S. Pat. No. 4,636,634 discloses a system where a bar code reader determines the presence of a manufactured article, such as a semiconductor device, in a bin wherein a wafer cassette box is provided with a suitable bar code.
It has been known to label liquid containers, such as bottles, with identification codes so they can be located and tracked throughout a system. U.S. Pat. No. 4,855,909 and U.S. Pat. No. 5,028,769 disclose the use of such codes on liquid containing bottles. Other approaches have been taken to control the volume and timing of the flow of liquids into a mixing container, such as that disclosed in U.S. Pat. No. 4,976,137.
However, no effective system has been designed to permit optical scanning or sensing of the contents of the container and tying the scanning of such a label to the opening or closing of a valve to ensure that only the proper liquid of the proper concentration enters a working apparatus.
A need exists for a reliable system to ensure that human operators do not fill or refill a working apparatus, such as a spray etching tool utilizing cleaning etching solutions employed in the semiconductor industry, with the wrong chemical or the wrong concentration. A serious problem can result if the wrong concentration chemical, such as an acid, or the entirely wrong chemical, such as hydrofluoric acid instead of sulfuric acid, is added or used to fill or refill a working apparatus. Such mistakes can destroy entire lots of expensive products, such as semiconductor wafers, damage the working apparatus, or both.
These problems are solved in the design and process of the present invention by utilizing a sensing system which determines from the label on the container the liquid being employed and determines whether that liquid is a proper match for the working apparatus and the valve controlling the flow of liquid into that apparatus. The design and process of the present invention provide prevent the filling of a working apparatus with the improper chemical, so that an automated control valve opens only when a proper match is made between the supply or fill container and the working apparatus.